The turbulence level affected the upward transport of pollen
(e.g. see the theoretical profiles proposed by Chamecki et al.,2007). For example, on17 July from0900 to 1000 EDT,highpollen
concentrations were sampled at z/h = 1 while sw was relatively
low 0.1–0.2ms1, close to the presumed threshold level of
becoming airborne. Such a low level would limit the vertical
upward transport of the pollen grains as indicated by a lowratio
of c(z/h = 2)/ch. As the wind picked up and the magnitude of
sw increased, the fraction of emitted pollen at canopy height
that reached twice this height, c(z/h = 2)/ch, increased.